1. Field
This invention relates to prototype modeling techniques. It is particularly directed to the construction of solid patterns derived from 3D CAD software-generated models.
2. State of the Art
Current rapid prototyping (RP) technology offers many advantages over more traditional prototyping techniques. For example, RP decreases the time required to produce an initial prototype. Currently available RP systems are generally flexible, and produce prototypes of superior accuracy. Unfortunately, they are also significantly more expensive to utilize than are traditional systems. Available techniques include stereolithography, laminated object manufacturing, fused deposition modeling, selective laser sintering, and ballistic particle manufacturing. These techniques in general operate on a common paradigm. They each decompose the part into a series of layers or cross sections. The part is then constructed by sequentially creating each layer and bonding it to the previous layer. This bonding usually occurs automatically as a part of the layer creation process. In the case of laminated object manufacturing, each layer is bonded prior to cutting the outline of the cross section. In any event, while several different parts may be built simultaneously on a common build platform, each layer of each discrete part must be created in sequential order.
Traditional RP techniques incorporate various techniques for dealing with cantilever overhangs in the part during construction. A support structure is often created in stereolithography systems. In some systems, the excess material surrounding each cross section provides the necessary support. Parts with complex curves have little contact area with the support structure during the construction procedures of many existing RP techniques. For example, a sphere theoretically contacts the build platform at a single point. As the sphere is built up from this point contact, it can easily shift, destroying the registration of the layers. For a more generalized part, the operator must decide how to orient the part, attempting to minimize overhangs and maximize the support provided by the building platform.
Construction of prototype parts by the application of RP technology usually requires the use of high-priced materials. Prohibitive costs have limited the proliferation of RP application to well-financed users, typically large companies with correspondingly substantial development budgets and RP service bureaus which demand large fees. Schools and typical smaller enterprises often cannot justify the acquisition of RP systems. There is a need for an inexpensive system capable of making RP technology directly accessible to small businesses and students.